How do mass and weight differ?

Mass is in kg and does not change with place; weight is a force in newtons caused by gravity.

Does zero net force mean the object is at rest?

No, steady straight-line motion also has zero net force.

Why treat the blocks separately for tension?

Tension is internal to the pair, so it only appears when one block is analysed alone.

S4 Physics: Forces and Newton Laws Practice Paper 4

2026-11-01

Tutor Prep Guide · Secondary Physics

Paper four starts with 24 N on 4 kg and the weight of a 5 kg bag, then covers inertia, zero net force, friction, a 3 kg trolley and a lift, before joined blocks, a bullet in a barrel and the wrong divisor in a system.

Quick answer　6 m/s^2, 50 N, inertia, zero acceleration, 3 m/s^2, 3 m/s^2 giving 15 m/s and 37.5 m, 880 N, 2.5 m/s^2 with 10 N, 40 000 m/s^2 with 800 N, and divide by the total mass.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10 questions
Suggested time	25 minutes
Difficulty mix	Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1
Chapter	Chapter: S4 Physics: Forces and Newton Laws – Tutor Lesson Plan
Level	S4

02　Questions (10 items)

FoundationA net force of 24 N acts on a 4 kg box. Find the acceleration.
FoundationWhat is the weight of a 5 kg school bag on Earth (take g as 10 N/kg)?
FoundationWhy do standing passengers lean backwards when a bus suddenly pulls away?
FoundationWhat can you say about an object whose net force is zero?
IntermediateAn 8 kg crate is pushed with 32 N against 8 N of friction. Find the acceleration.
IntermediateA 9 N force pulls a 3 kg trolley on a frictionless track from rest for 5 s. Find the acceleration, the speed at 5 s and the distance.
IntermediateA lift with a passenger has a total mass of 80 kg and accelerates upwards at 1 m/s^2 (g = 10 m/s^2). Find the normal force from the floor.
ChallengeA 6 kg and a 4 kg block are joined by a light string on a smooth table and 25 N pulls the 6 kg block horizontally. Find the acceleration and the tension.
ChallengeA 0.02 kg bullet goes from rest to 400 m/s in a 0.01 s barrel. Find the acceleration and the average force.
Error redoA student computes the acceleration of a joined 4 kg and 6 kg system under 20 N as 20 / 6 = 3.33 m/s^2. What is wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	6 m/s^2 (24 / 4)	Use F = ma, so acceleration is force over mass.
2	50 N (5 x 10)	Weight is mass times g and is measured in newtons.
3	Their bodies tend to stay at rest, which is inertia	Inertia is the tendency to keep the existing state of motion.
4	The acceleration is zero, so it stays at rest or moves at steady speed in a straight line	Zero net force does not mean at rest; steady motion also counts.
5	3 m/s^2 ((32 – 8) / 8)	Find the net force first, then divide by the mass.
6	3 m/s^2, 15 m/s and 37.5 m	F = ma gives 3, then use v = at and s = half a t squared.
7	880 N (80 x (10 + 1))	Accelerating upwards needs more than the weight, so use m(g + a).
8	2.5 m/s^2 and a tension of 10 N	Use the 10 kg total for a, then apply it to the 4 kg block for the tension.
9	40 000 m/s^2 and an average force of 800 N	Use a = change in velocity over time, then F = ma.
10	The divisor should be the 10 kg total, giving 2 m/s^2	The whole-system method must include every mass being accelerated.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

Find a tutor free Tutor Registration →

Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.